Few-layer black phosphorus (BP) is an emerging material of interest for applications in electronics. However, lack of ambient stability is hampering its incorporation in practical devices as it demands for an inert operating environment. Here, we study the individual effects of key environmental factors, such as temperature, light and humidity on the deterioration of BP. It is shown that humidity on its own does not cause material degradation.In fact, few-layer BP is employed as a recoverable humidity sensor. This study eliminates humidity as an active parameter in BP degradation. Hence, by simply isolating BP from light, its lifetime can be prolonged even in the presence of O 2 . As such, this study opens the pathway for devising new strategies for the practical implementation of BP.

Narrow spectral sensitivity in materials is one of the crucial challenges to develop high-performance broadband photodetectors. Here, we design a heterostructure of two-dimensional molybdenum disulfide (MoS2) and epitaxial gallium nitride (GaN) films to create an enhanced spectral absorption profile. This combination utilizes complementary optical absorption of MoS2 (visible) and GaN (UV) driven by type II band alignment at their interface to showcase highly sensitive photodetectors spanning across the UV–NIR regime. Concurrently, the heterostructure exhibits significantly enhanced responsivity (order of 104 A/W) and external quantum efficiency that are 500% higher than the bare GaN photodetectors. Given the available scalable synthesis approaches that have now been designed by the research community for both constituent materials, the demonstration of this heterostructure as a broadband photodetector with high figures-of-merit opens opportunities in designing efficient optoelectronic junctions and imaging applications.

Two-dimensional (2D) molybdenum trioxide has been attracting research interest due to its bandgap tunability and a wide variety of desirable electronic/optoelectronic properties. However, the lack of a reproducible synthesis process for obtaining large coverage 2D MoO3 has limited the use of this material. Here we report the synthesis of large area 2D MoO3-x via physical vapor deposition, using MoO3 powder as the precursor. The as-grown layers are directly deposited on SiO2/Si, eliminating the necessity for any transfer process. These as-grown MoO3-x layers allow for the large-scale fabrication of planar device arrays. The applicability of 2D MoO3-x in optoelectronics is established via the demonstration of low-power ultraviolet (UV) sensor arrays, with rapid response times (200 µs) and responsivity up to 54.4

Metal oxide-based gas sensor technology is promising due to their practical applications in toxic and hazardous gas detection. Orthorhombic α-MoO3 is a planar metal oxide with a unique layered structure, which can be obtained in two-dimensional (2D) form. In 2D form, the larger surface to volume ratio of the material facilitates significantly higher interaction with gas molecules while exhibiting exceptional transport properties. Presence of oxygen vacancies results in non-stoichiometric MoO3 (MoO3-x), which further enhances the charge carrier mobility. Here, we study dual gas sensing characteristics and mechanism of 2D α-MoO3-x.Herein, conductometric dual gas sensors based on CVD grown 2D α-MoO3-x are developed and demonstrated. A facile transfer process is established to integrate the material into any arbitrary substrate. The sensors show high selectivity towards NO2 and H2S gases with response/recovery rates of 295.0 kΩ/s and 276.0 kΩ/s towards NO2, and 28.5 kΩ/s and 48.0 kΩ/s towards H2S, respectively. These gas sensors also show excellent cyclic endurance with a variation in ΔR ~112 ± 1.64 MΩ and 19.5 ± 1.13 MΩ for NO2 and H2S, respectively. As such, this work presents the viability of planar 2D α-MoO3-x as a dual selective gas sensor.

This work demonstrates a simple method for fabricating nearly spherical dome structures on top of lithographically defined microfluidic channels using gallium based liquid metal droplets as fugitive ink. The droplets remain stable during the pouring and curing of polydimethylsiloxane (PDMS) and can be easily removed by applying a basic solution. This facilitates the formation of domes with diameters of a few hundred microns patterned on the desired locations of the channel. The expansion of the channel at the interface of the dome leads to formation of a large vortex inside the dome. Experiments using high-speed imaging along with numerical simulations show the utility of the vortex-induced flow rotation for orbiting of human monocytes and polystyrene microbeads inside the dome. The lateral displacement of liquids caused by the vortex is further utilized for creating controllable This article is protected by copyright. All rights reserved. multiband flow/color profiles within a T-mixer. Our method enables the fabrication of customized, complex and 3D microfluidic systems utilizing planar microfabricated structures.Received: ((will be filled in by the editorial staff))Revised: ((will be filled in by the editorial staff)) Published online: ((will be filled in by the editorial staff))